Field of vision (FOV) is the angular extent of the observable world that can be seen at a given moment. The FOV for a person of normal vision is around 120 degrees. However, a visually impaired person can have a much contracted FOV. For example, a person with Retinitis Pigmentosa (RP) has a FOV of 20 degrees or less. Such a person is often classified as legally blind.
The American Foundation for The Blind (AFB) estimated that the legally-blind population is about 1.3 Million in the United States. As a pedestrian, a blind or visually impaired person runs a far greater risk to be involved in serious traffic accidents. Many blind or visually impaired people in the United States use mobility canes to guide them around. A conventional mobility cane, however, only provides a very limited amount of information about a user's surrounding environment, usually about the objects that may be physically touched by the cane.
Various other devices have been developed to provide a blind or visually impaired person information about his or her surrounding environment beyond the physical reach of a conventional cane. For example, an acoustic cane can provide information through sound feedback (echolocation). When an acoustic cane is used, it sends out audio signals that reflect or echo from objects within the user's surrounding environment. The user interprets the echoes to decipher the layout of the environment. Other devices send out light signals that reflect from objects surrounding the user. The reflections are then converted into audible signals such as a click or a variably pitched beep to convey information about the surrounding objects back to the user.
U.S. patent application Ser. No. 10/519,483 (Publication Number US 2006/0098089 A1) discloses an apparatus including electro-optical devices to detect and identify objects. A control unit is used to receive and process information from the devices. A vocal representation unit is then used to receive instructions from the control unit for purpose of audibly describing the objects to the user.
Devices relying on audio signals to convey information regarding surrounding environment to a user are ill suited for noisy environments such as heavily trafficked streets or for deaf-blind individuals who are incapable of hearing the audio signals. In such situations, it is desirable to have an apparatus and method to convey surrounding environment information through non-audio signals.